It is often necessary, particularly in the aircraft industry, to install a high strength externally and internally threaded insert in relatively soft material in order to increase the holding power of a fastener in the soft material. Such inserts often have longitudinally advanceable keys that mechanically lock the insert in the relatively soft material. Heretofore, the keys have been driven to the locked condition by a secondary operation which, in most instances, consists of merely hammering the keys into position.